Cope rearrangement



The Cope rearrangement is an extensively studied Arthur C. Cope. For example 3-methyl-1,5-hexadiene heated to 300°C yields 1,5-heptadiene.

The Cope rearrangement causes the bullvalene family.

Mechanism

Although the Cope rearrangement is chair conformation, the Cope can also occur with cyclohexadienes in the "boat" conformation.


Examples

The rearrangement is widely used in organic synthesis. It is symmetry-allowed when it is 1,5-cyclooctadiene ring:


In this case, the reaction must pass through the double bonds. A trans double bond in the ring would be too strained. The reaction occurs under thermal conditions. The driving force of the reaction is the loss of strain from the cyclobutane ring.

Variations

Variations of the Cope rearrangement are the Oxy-Cope rearrangement and Heteroatom Cope reactions such as the Aza-Cope rearrangement. Another widely studied [3, 3] Claisen rearrangement.

References

  • Cope, A. C.; et al.; J. Am. Chem. Soc. 1940, 62, 441.
  • Rhoads, S. J.; Raulins, N. R.; Org. React. 1975, 22, 1-252. (Review)
  • Hill, R. K.; Comp. Org. Syn. 1991, 5, 785-826.
  • Wilson, S. R.; Org. React. 1993, 43, 93-250. (Review)
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Cope_rearrangement". A list of authors is available in Wikipedia.